Last week, about 10 miles off the coast of Dana Point, California, Capt. Larry Hartmann found his boat in the middle of a swarm of finback whales, a rare event by itself, according to Grind TV. The event left him and the four passengers in awe.

But then they got an even rarer treat.

One of the whales, measuring about 60 feet long, decided to do a little twirl for the boat, giving them a full view of its underside. By comparison, the boat only measured 34 feet in length.

There were between 6-10 fin whales, each measuring about 60 feet, and at times they'd accelerate as they neared the boat, then dive beneath its hull. At several points he was concerned for the safety of his passengers because a collision appeared imminent, and fin whales have been known to breach.